Rod,
Yes its a 1984 Lario. Could you let me know the problem that you feel this model has as this is my first Guzzi ( YES got one at last
). I think the gear noise may be a dry spot on top gear as this bike has done a lot of sitting (only 25000 Km). I will have to crack open the box and have a look but after I get a bit of riding in first and some enjoyment, and I'm not a thrasher and rarely get it into top. I've been told about the possible valve issue and the debate on whether to change valves, change springs or change both? Don Newell says just go heavier springs and he has worked on them for near on 35 yrs. Others say go lighter springs as its the spring pressure snapping them. My brother has been a engine reconditioner for 40yrs and done professional drag racing and worked on others drag cars and as soon as I mentioned snapping valves he said straight up heavier springs as he saw this heaps on drag motors and its due to valves not full slamming shut and the stems getting hot spots and letting go. Seeing that he is sperm related to me I suppose I'll have to believe him? I seem to have solved the oil light problem by change of fuel, carby clean and sync. It runs 100% better and doesn't feel like a deisel tractor anymore and idles purrrfect on 1000rpm. I'm getting used the long throw shifter and I thought all my british oil leakers had long shifts. I suppose Japs perfected short shift for there small feet and the Poms are well just Poms but us real men can handle the Guzzi shifter 
. I can not source a english workshop manual either so any help in this would also be appreciated.Tony